1. Field of the Invention
The present invention relates to a method of optical power calibration performed by the optical storage carrier player, such as the CD-R/RW drive, and more particularly, to a method of optical power calibration where calibration is performed at the outer edge of an optical storage carrier, such as a compact disc (CD).
2. Description of the Prior Art
CD-R and CD-RW drives (optical storage carrier player) now are popular PC peripherals. In general, the CD-R/CD-RW drive performs an optical power calibration before actually writing data onto a compact disc (CD, optical storage carrier), such as: CD-R/CD-RW disc. The purpose of the optical power calibration is to determine a optimized writing optical power. Typical optical power calibration involves writing information to a power calibration area (PCA), which is located closed to the central portion of a CD disc. This information written on the power calibration area through the power calibration is read back, and the CD-R/CD-RW drive determines an optimized optical power from the signal reflected from the CD disc, and then the CD-R/CD-RW drive writes further data onto the CD disc by applying the optimized optical power.
Please refer to FIG. 1. FIG. 1 is a side view of a CD 10. The CD is a thin circular disk that is symmetrical about a centerline 11. The CD's specification is given in the Orange Book. The CD 10 comprises a central portion 12, a Power Calibration area (PCA) 14, located outside the central portion 12, a data storage area 16, located outside the PCA 14, and a last possible lead-out area 18, located near the CD outer edge.
Please refer to FIG. 2. FIG. 2 is a perspective view of the PCA 14 shown in FIG. 1. The PCA 14 comprises a test area 20 which allows a test data written thereon during the power calibration, and a count area 22 in which a count of the number of power calibrations already performed in the PCA 14 is recorded. According to the specification in the Orange Book, the test area 20 and the count area 22 are divided into 100 partitions 20a, 22a, respectively. Therefore, the optical power calibration can be performed up to 100 times.
However, after the CD disc is unloaded from the tray or the tray is moving out once, at least one optical power calibration is necessary to be performed for starting a new data writing action. According to the CD-disc standard described in the Orange Cook, the 100 partitions available on the PCA limit the number of times available for writing to CD-R disc.